The current trend in the medical industry is to make life-saving portable medical devices, such as automated external defibrillators (AEDs), more widely accessible. As the availability of portable medical devices continues to increase, more places will have these devices for use in emergency situations. However, this increase also comes with the heightened likelihood that these portable medical devices will be used by people without medical training. The advantage of having a life-saving medical device immediately available to a lay person is then fully realized when use of the device is followed by professional emergency medical care. For AEDs, the increase in survival rate made possible by early defibrillation is enhanced when advanced life support (ALS) providers can arrive on the scene in a timely fashion. Indeed, the American Heart Association (AHA) recommends that early defibrillation be followed by care provided by persons trained in ALS. This presents two requirements for AEDs: (1) ALS providers must be promptly notified that an AED is being used; and (2) ALS providers must be given the location of the AED.
Previous attempts to meet these two requirements have included the use of a global positioning system (GPS) receiver to obtain the AED's location and a cellular telephone to give the location to ALS providers. The GPS receiver, when fully functional, is advantageous because often times the person making a call to ALS providers is not aware of, or mistaken about, his exact location, especially in case of emergency. The problem is that current GPS receivers do not work well in metal buildings, or “urban canyons,” due to signal interference and blockage. Thus, although a cellular telephone could be used to alert ALS providers that an AED is being used, it cannot give the device's location to ALS providers when the device is used in certain unfavorable locations.